1. Field of the Invention
The present invention relates to a fabricating apparatus for a light tunnel and a fabricating method for fabricating a light tunnel, and more particularly, to a fabricating apparatus and a fabricating method that use inner dimensions of a light tunnel as a reference for fabricating the light tunnel.
2. Descriptions of the Related Art
With continuous advancement of projection technologies, the applications of projectors have become wider and consumers now have more options in purchasing projectors. Accordingly, the imaging quality requirements of the projectors have become increasingly heightened. A projector comprises a lot of optical components, and the characteristics of the individual optical components have different effects on the imaging quality of the projector. Projection luminance is known to be an important indicator of imaging quality, so most projection optics researches spend their research and development resources on improving projection luminance. A usual practice for improving the projection luminance adopted in this industry is to enhance the reliability of components of the projector's illumination system, to reduce the overall volume of the illumination system and to improve efficiency of the light source.
The illumination system usually comprises a light source module, a lens, a light tunnel and the like. Generally, the light tunnel is used to uniformize the projection light, so it is able to control the projection luminance. Therefore, usually in practice, various parameters and the quality of the light tunnel are adjusted to improve the efficiency of the light source to improve the luminance of the images obtained.
In more detail, the light tunnel is able to uniformize the light transmitted therethrough and project the light onto an active region of a spatial light modulation device to effectively avoid non-uniformity of luminance in a specific light path of the optical projection system. However, the control of the projector luminance is significantly affected by inner profile dimensions of the light tunnel.
Most conventional fabricating processes of light tunnels fabricate a light tunnel through external positioning. FIG. 1A shows a schematic view of a fabricating apparatus 1 that uses outer dimensions of a light tunnel to position the light tunnel. During the fabrication process, a reflecting sheet stopping device 11 of the fabrication apparatus 1 is first adjusted to an appropriate position. Next, in reference to FIG. 1B, reflecting sheets 12 for forming the light tunnel are placed in sequence, and an inhaling switch (not shown) is opened to adsorb the reflecting sheets 12 onto ports of corresponding inhaling pipes 13 as shown in FIG. 1C. In reference to FIG. 1D, a pressing block 15 is placed on the top of the light tunnel 14 and an external pressure that is exerted by an elastic pressing head 16 is adjusted, then the elastic pressuring head 16 is lowered to fix the reflecting sheets 12 of the light tunnel 14 together, and finally the reflecting sheets 12 are glued into form.
For the fabricating process described above, a corresponding fabricating apparatus is first designed according to the outer dimensions of the light tunnel, and then the light tunnel is assembled by adjusting the fabricating apparatus, so that the inner profile dimensions of the light tunnel are guaranteed indirectly by use of the outer dimensions. However, this practice of fabricating a light tunnel through external positioning has several problems. Especially, because the inner profile dimensions of the light tunnel are determined through external positioning in the aforesaid practice, there are too many factors that have an effect on the inner profile dimensions, e.g., thicknesses of the reflecting sheets, inhaling forces of the inhaling pipes when the reflecting sheets are positioned, the operation mode and the flow process of adjusting the fabricating apparatus. Furthermore, this fabricating process is complex and makes it difficult to control the inner dimensions, which renders the product quality unstable in mass production.
Accordingly, an urgent need exists in the art to provide a fabricating apparatus for a light tunnel which can improve the imaging luminance by effectively controlling the inner dimensions of the light tunnel.